An Evaluation of State Laws Intended to Curb High-Risk Opioid Prescribing Opioid overdose deaths continue to increase in the U.S., with over 30,000 deaths in 2015. This epidemic is driven in large part by the high volume of opioids prescribed by healthcare providers. States have begun to enact laws designed to curb certain high-risk opioid prescribing practices, such as high-dose prescribing and overlapping opioid and benzodiazepine prescriptions, which are associated with misuse and mortality. Most recently, state efforts have centered on four types of laws. First, mandatory prescription drug monitoring program (PDMP) enrollment laws. While they exist in 49 states, only 35% of controlled substance prescribers report enrolling with PDMPs, or databases of controlled substance prescriptions that healthcare providers can access to learn about patients? past and current prescription drug use. To increase PDMP use, 20 states have enacted mandatory PDMP enrollment laws, which require prescribers to enroll in ? and thereby gain access to ? their state?s PDMP. Second, mandatory PDMP query laws, which require providers to check the PDMP prior to prescribing opioids, have been enacted in 20 states. Third, pill mill laws, which strictly regulate pain clinics to prevent rogue clinics from issuing opioid prescriptions without medical indication, have been enacted in 11 states. Fourth, opioid prescribing cap laws, which limit days? supply and/or dose of prescribed opioids, have been enacted in seven states. The effects of these laws on high-risk opioid prescribing are largely unknown. Using qualitative interviews and Quintiles LifeLink LRx/Dx prescription and outpatient claims data we propose a mixed methods study of how these four types of laws independently affect high-risk opioid prescribing. We will focus on 18 ?treatment states? that enacted one of the four types of laws of interest ? but no other laws designed to curb high-risk opioid prescribing ? over a four-year period. We propose to: 1) explore the implementation and enforcement of the four types of laws in each of the 18 treatment states; 2) study the independent effects of these four types of state laws on high-risk opioid prescribing patterns; and 3) study the independent effects of the four types of laws on substitution of non-opioid pain treatments among individuals diagnosed with non-cancer chronic pain. For Aims 2 and 3 we will conduct synthetic control analyses comparing pre/post law trends in opioid prescribing in each treatment state to trends in a weighted combination of comparison states. A key strength of the proposed study is our ability to disentangle the causal effects of each of the four types of laws of interest on high-risk opioid prescribing. The mixed methods approach is another significant contribution: the results of our Aim 1 interviews will directly inform the design and interpretation of Aims 2 and 3. In the face of continuing increases in opioid overdose deaths and limited resources, state lawmakers need research evidence to inform decisions about policy enactment and implementation. The proposed study will fill critical gaps in knowledge regarding the effectiveness and implementation of state laws designed to curb high-risk opioid prescribing.